In known building practice, formwork is assembled on a surface or on a lower floor level to form the next level of the building above. The formwork includes box forms to create columns, table forms to form concrete beams extending between the columns and lost formwork to fill the regions between the beams.
Lost formwork and the table forms are normally held in position by scaffolding. The scaffolding is assembled on to the surface or floor below with the lost formwork and table forms being supported on the scaffolding. The table forms are lowered in to position on to the scaffolding by cranes.
The lost formwork comprises rolled sheet metal sections which are left place after the concrete sets.
The table forms normally have plywood surfaces against which the concrete is poured. A series of joists are spaced along the underneath surface of the plywood and further bearers are located under the joists which locate on the scaffolding to support the formwork.
The scaffolding is strong enough to support concrete which is then poured on to the formwork to create the next floor above. Once this concrete is set, and becomes self supporting, then the scaffolding and formwork can be removed from beneath.
Normally, scissor lift mechanisms or platforms are used to support the table forms while the scaffolding is removed. The table form formwork is then prised away from the concrete surface and lowered to ground level. All the components are stacked for the removal from the building site by forklift and crane.
In the past, it has been proposed to use carriage systems to replace scaffolding to allow raising and lowering of the concrete formwork. An example of this is shown in British Patent No. GB1052097. According to this specification, the formwork can be raised to the required position and supported there while the concrete is poured on above. Once the concrete is set, then the concrete formwork is lowered to then be removed.
However, a significant problem with this process is the adherence of the formwork to the concrete surface. Force is required to part the formwork from the concrete surface, and this is normally achieved by levering the formwork away from the surface. The arrangement shown in the British Specification referred to above will not pull the formwork down. The adherence to the formwork to the concrete is such that the formwork will remain on the concrete as the frame is lowered.
It is against this background and the problems and difficulties associated therewith that the present invention has been developed.
Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.